Bonding textile materials to rubber containing hexamethyl ether of hexamethylolmelamine



United States Patent Claims priority, application Great Britain, Nov. 30, 1962,

45,279/ 62 Int. Cl. B32b 25/10, 27/42; C09j 3/12 U.S. Cl. 156-334 Claims ABSTRACT OF THE DISCLOSURE A method of bonding textile materials to rubber compositions by means of phenol-formaldehyde bonding agents, in which the formaldehyde is generated from a compound which is stable up to temperatures from 100- 150" C. and consisting of ethers of hexamethylolmelamine.

This application is the continuation of U.S. application, Ser. No. 323,883 filed Nov. 15, 1963 now abandoned.

This invention relates to the bonding of textile materials to rubber.

In the production of composite articles of textiles and rubber in which the textile serves to reinforce the rubber it is essential to provide a good bond between the textile component and the rubber component.

This is important, for example, in the production of articles such as pneumatic tyres, mechanical belting and hose in which the textile is generally used in the form of cords.

It is known that improved adhesion between rubber compositions and textile materials is obtained by first treating the textile with a suitable adhesive such as an aqueous dispersion of an incompletely condensed phenol-aldehyde in admixture with a natural latex or a synthetic latex such as a terpolymer of butadiene, styrene and vinyl pyridine.

It has now been found that by a specific modification of the rubber composition improved adhesion of rubber to textile material can be obtained.

According to the present invention a method of bonding a textile material to a natural or synthetic rubber composition comprises incorporating in the said composition a polyhydric phenol, a stable formaldehyde-generator as hereinafter defined and vulcanizing ingredients, applying the textile material to the resulting rubber composition and vulcanizing the assembly.

By a stable formaldehyde-generator in this specification there is meant a compound which is substantially stable up to temperatures between 100 C. and 150 C.

Examples of formaldehyde-generators suitable for use in this invention are hexamethoxymethylmelamine, lauryloxymethyl pyridinium chloride, cethyloxymethyl pyridinium chloride, ethyl oxymethyl pyridinium chloride and also polymers of formaldehyde having stabilizing groups, or residues of substances such as pentaerythritol, at the ends of themolecule.

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Such polymers of formaldehyde as paraformaldehyde, metaldehyde and trioxymethylene readily lose formaldehyde at temperatures lower than C. and improvement in adhesion when such polymers are used is generally not so great as with the stabilized formaldehyde-generators and, moreover, cannot be relied upon.

The stable formaldehyde-generators of this invention are present preferably in an amount of from 0.5 part to 6 parts per 100 parts of the rubber elastomer in the rubber composition.

The preferred polyhydric phenols are the metadihydroxy phenols such as resorcinol; 1,5-naphthalene diol can also be used and the polyhydric phenol is incorporated in the rubber composition preferably in an amount of from 05 part to 6 parts per 100 parts of the rubber elastomer in the rubber composition.

The textile material can consist of any of the well known natural or synthetic textile materials. The invention is of particular value in the bonding of cords such as rayon.

and nylon cords. Improved adhesion is obtained by the method of the invention both when the textile material is untreated and also when the textile is previously treated with one of the conventional latex resorcinol formaldehyde cord adhesives.

Rubber compositions which can be used include any of the conventional compositions based on natural rubber, butadiene/styrene rubbers, chloroprene rubbers, nitrile rubbers and blends thereof, and other butadiene copolymers it being desirable to incorporate the polyhydric phenol and the formaldehyde-generator prior to the addition of thevulcanizing ingredients. In a preferred method the polyhydric phenol is incorporated with all the other compounding ingredients except the sulphur and the accelerators of vulcanization into the rubber in an internal mixer to ensure optimum dispersion of the phenol in the rubber, and the formaldehyde-generator is added later, on a rubber mill, immediately before the incorporation of the vulcanizing ingredients.

The invention is illustrated by the following examples, all parts being parts by weight:

EXAMPLE I A conventional natural rubber compound was used and various proportions of resorcinol and of hexamethoxymethylmelamine were incorporated. The basic compound had the following composition:

Rubber compositions having the above formulation and also with varying amounts of added resorcinol and hexamethoxymethylmelamine, as indicated in parts per 100 parts of rubber in the tables, were used and cords adhered therein, the assemblies then being vulcanized for 25 minutes at 148 C. (50 p.s.i. steam). The strength of the by low temperature copolymerization, and Pdtq to polym erized 1,2-dihydro-2,2,4-trimethylquinoline.

bond between the cords and the rubber was measured by Parts the pull-through test described by J. 0. Wood, Trans Natural rubber 700 I.R.I., 32, l, l to 18 (1956). B/S The pull-through force figures, in pounds, required to a F ast extruding furnace black 30.0 remove one centimetre of adhered nylon or rayon cord Zinc Oxide 0 from the cured rubber, are given in the following tables, Sulphur each figure being the average of 15 pull-through tests. Stearic The nylon cord used was 2 yarn 840 denier and the rayon Mercaptobee i i g l bb f h h Tetrarnethylthiuradisulphide 0.05 g g z i m is an a revlatlon or examet Oxy- N-cyclohexyl-2-benzthiazole sulphenamide 0.5 N-nitrosodiphenylamine 0.5 TABLE I.UNTREATED corms Pdtq Pine tar 3.0 Hm Nylon Rayon Mineral i 3.0 RQSOICIHOI- 0 L3 L0 Tyre reclalm 60.0

i 'i 203 5 310 1211 0:4 m0 Rubber compositions were prepared having varied amounts of resorcinol and hexamethoxymethylmelamine The effect of the Presence of resorcinol and heXa and nylon and rayon cords treated with cord adhesives methoxymethylmelamine in the rubber composition upon as i E l 1 (T bl II d III ti l were its adhesion to treated nylon and rayon cords was also prepared and bonded in these rubber compositions. determined. The two types of cord were treated each I hi example pull-through (d t t were d with a different latex resorcinol formaldehyde dispert a temperature of 100 C d th lt given i sion or dip. The two latex dips had the following T bl IV were bt i d formulae, all parts being parts by dry weight, the total solids content and minimum maturing time for each TABLE IV dip being also specified in the formulae: Hm Rayon Nylon B/s/vp is a 70/15/15 butadiene/styrene/vinyl pyri- Rcsorcino]; dine terpolymer and B/s(c) is a 75/25 butadiene/ styrene 1 3-2 copolymer prepared by cold polymerization. 22 12:8 1013 2.0 14.9 10.6 3.3 14.0 11.2

Nylon Dip Rayon Dip Resorcinol, t; 11 1 The results Sl'lOWl'l in Table IV indicate that the addigggfifi fi ggg gg 8- 9 g g tion of resorcinol and hexamethoxymethylmelamine to ,ii 10010 1 40 the rubber composition results in improved hot ad- 5?- 5 3:2 hesion between dipped cords and the rubber composi- Metering time, hours 6 24 tron for both rayon and nylon.

EXAMPLE III TABLE II-TREATED NYLON CORD Using natural rubber composition described in Exam- Hm Adhesion ple I as the basis, amounts of resorcinol and hexamethoxymethylmelamine as parts per hundred parts of 3??? 0 1&6 rubber were incorporated as shown in Table V.

18% Nylon and rayon cords were treated with the nylon 3: 1 1 dip as described in Example I, except that the total 44 solids content of the adhesive was reduced from 20 percent to 10 percent. Vulcanization and testing were as Table III shows the improved wet adhesion for treated for Example I, the adhesion tests helng carried out at rayon cord obtained when the rubber composition conroom temperaturetained resorcinol and hexamethoxymethylmelamine, the TABLEV test samples having been soaked in water for 24 hours Hm Rayon Nylon before the test was made. Resorcinoy 0 0 20.2 14.9 TABLE III.-TREATED RAYON CORD 1.8 27.8 17.4 2.4 28.8 20.9 Hm Wet Adhesion 3.0 29.2 18.8

Resgrcinol: 0 6 8 1 Indicates cord break at the average pull given in the table.

-l 8-2 The adhesion figures of Table V show the improved bonding obtained between both rayon and nylon cords 5 previously treated with a latex resorcinol formaldehyde The results of Example I Show h both Wlth untreated adhesive, and a natural rubber composition, when there and pp rayon cords the additloh of resorcinol and is incorporated in the rubber composition both resorcinol hexamethoxymethylmelamine to the rubber composition d hexamethoxymethylmelamine. The figures also make gives improved adhesion, as indicated by the pull-through clear that further increased adhesion obtained when the figures. hexamethoxymethylmelamine content of the composi- EXAMPLE II tion is increased from 1.8 to 2.4 parts per 100 parts of rubber elastomer in the rubber composition. In this example, there was used a rubber composition wh i l i d i having the following basic formula in which B/s re- 1, A method of improving the process of bonding a fers to a 72/18 butadiene/styrene copolymer produced 75 textile material to a rubber composition which com- 5 prises incorporating in said composition vulcanizing ingredients, a polyhydric phenol and hexamethyl ether of hexamethylolmelamine, applying the textile material to the resulting rubber composition and vulcanizing the resulting rubber composition.

2. A method according to claim 1, in which the polyhydric phenol is resorcinol.

3. A method according to claim 1, in which the polyhydric phenol is present in an amount of from 0.5 to 6 parts per 100 parts by weight of the rubber in the rubber composition.

4. A method according to claim 1, in which the hexamethylolmelamine ether is present in an amount of from 0.5 to 6 parts per 100 parts by weight of the rubber in the rubber composition.

5. A method according to claim 1, in which the tex tile material has been previously treated with a latex resorcinol cord adhesive.

References Cited UNITED STATES PATENTS OTHER REFERENCES Polymer Processes, Schildknecht, C. E., pp. 338, 339

10 Interscience Publishers, New York City, 1956.

JOHN T. GOOLKASIAN, Primary Examiner C. B. COSBY, Assistant Examiner US. Cl. X.R. 

